Heretofore, semi-additive circuitry with raised features have been manufactured utilizing a solid sheet of stainless steel as the mandrel. Crumly et al, U.S. Pat. No. 5,207,887 issued May 4, 1993, the disclosure of which is hereby incorporated by reference, sets forth such a process. In the prior art, solid sheets of stainless steel 0.06 inches thick or thicker were used for mandrels. However, as mandrel sizes became larger, the weight of the mandrel became excessive and difficult to move from station to station in any type of automated semi-additive circuitry manufacturing process.
The present invention provides alternatives and advantages over the prior art.